Method for etching etch layer

ABSTRACT

A method includes rotating a wafer, dispensing a liquid from a center of the wafer to an edge of the wafer to control a temperature of the wafer, and etching an etch layer of the wafer with an etchant during or after dispensing the liquid. The liquid is dispensed through a nozzle.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No. 14/696,973, filed Apr. 27, 2015, issued as U.S. Pat. No. 10,283,384 on May 7, 2019, which is herein incorporated by reference in its entirety.

BACKGROUND

Etching is used in microfabrication to chemically remove layers from the surface of a wafer during manufacturing. Etching is a process module, and every wafer undergoes many etching steps before it is complete. For many etch steps, part of the wafer is protected from the etchant by a “masking” material which resists etching. In some cases, the masking material is a photoresist which has been patterned using photolithography. Other situations require a more durable mask, such as silicon nitride.

The wafer can be immersed in a bath of etchant, which must be agitated to achieve good process control. For instance, buffered hydrofluoric acid (BHF) is used commonly to etch silicon dioxide over a silicon substrate. Different specialised etchants can be used to characterise the surface etched.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 is a partial view of a wafer etching apparatus according to some embodiments of the present disclosure;

FIG. 2 is a flow chart of a method for etching an etch layer according to some embodiments of the present disclosure;

FIG. 3A is a diagram of etch profile of the etch layer on the front side of the wafer under a process configuration, in which the X-Axis is distance from wafer center and Y-Axis is the etch Amount;

FIG. 3B is another diagram of etch profile of the etch layer on the front side of the wafer under another process configuration;

FIG. 4 is a partial view of a wafer etching apparatus according to some embodiments of the present disclosure;

FIG. 5 is a partial view of a wafer etching apparatus according to some embodiments of the present disclosure;

FIG. 6A is a partial view of a wafer etching apparatus according to some embodiments of the present disclosure, in which the preheated/precooled liquid is dispensed to the wafer;

FIG. 6B is another partial view of FIG. 6A, in which the heated etchant is dispensed to the wafer;

FIG. 7 is a flow chart of a method for etching an etch layer according to some embodiments of the present disclosure;

FIG. 8A is a partial view of a wafer etching apparatus according to some embodiments of the present disclosure, in which the preheated/precooled liquid is dispensed to the wafer;

FIG. 8B is another partial view of FIG. 8A, in which the heated etchant is dispensed to the wafer;

FIG. 9 is a partial view of a wafer etching apparatus according to some embodiments of the present disclosure;

FIG. 10 is a partial view of a wafer etching apparatus according to some embodiments of the present disclosure; and

FIG. 11 is a partial view of a wafer etching apparatus according to some embodiments of the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

As used herein, “around”, “about” or “approximately” shall generally mean within 20 percent of a given value or range. Numerical quantities given herein are approximate, meaning that the term “around”, “about” or “approximately” can be inferred if not expressly stated.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising”, or “includes” and/or “including” or “has” and/or “having” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.

It will be understood that when an element is referred to as being “on” another element, it can be directly on the other element or intervening elements may be present therebetween. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Reference will now be made in detail to the present embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.

Layers (e.g., poly-Si/SiO2) might be etched at moderately high temperature (e.g. 60° C.) or at room temperature (e.g., 25° C.). However, etch layer removal requires high temperature reactants (e.g., 200° C.) to effectively remove silicon nitride layer. While etchants are heated for this, it is consistently observed that the temperature fluctuation across a wafer that is at room temperature is severe. That is, the situation adversely affects process control and etching uniformity for the etching process. To solve the problem, the disclosure is proposed to preheat the wafer before dispensing the heated etchants, so at to well regulate and control temperature, to rapidly ramp temperature, and to get better uniformity across the wafer.

FIG. 1 is a partial view of a wafer etching apparatus 1 according to some embodiments of the present disclosure.

As shown in FIG. 1 , the wafer etching apparatus 1 is a single wafer tool. The wafer etching apparatus 1 may be contained within a hermetic chamber (not shown). The hermetic chamber may avoid contamination and maintain environmental stability within the wafer etching apparatus 1. The wafer etching apparatus 1 is configured to perform an etching process, specifically a wet etching process, on a wafer W. In the depicted embodiments, an etch layer is formed on a front side of the wafer W (i.e., the upper side of the wafer W in FIG. 1 ), and the wafer etching apparatus 1 is configured to etch the etch layer. In some embodiments, the etch layer EL is a silicon nitride layer, but the disclosure is not limited in this regard. The wafer etching apparatus 1 may completely etch the etch layer EL or remove portions of the etch layer EL, such that a patterned etch layer EL remains after the etching process.

As shown in FIG. 1 , the wafer etching apparatus 1 includes a first flow channel 10 a, a second flow channel 10 b, a temperature-regulating module 11 a, a heater 11 b, a first nozzle 12 a, a second nozzle 12 b, a first mass flow controller 13 a, a second mass flow controller 13 b, a chuck 14, and a base 15. The chuck 14 is configured to hold the wafer W. The first flow channel 10 a is configured to carry a liquid LQ for controlling a temperature of a back side of the wafer W. The temperature-regulating module 11 a is coupled to the first flow channel 10 a. The temperature-regulating module 11 a is configured to controlling a temperature of the liquid LQ in the first flow channel 10 a. The first mass flow controller 13 a is coupled to the first flow channel 10 a. The first mass flow controller 13 a is configured to measure and control the flow of the liquid LQ at a particular range of flow rates. The first nozzle 12 a is coupled to the first flow channel 10 a and located right under the back side of the wafer W. The first nozzle 12 a is configured to dispense the liquid LQ to the back side of the wafer W (i.e., the lower side of the wafer W in FIG. 1 ). The base 15 is located at the back side of the wafer W and forms a gap with the back side of the wafer W. The first nozzle 12 a is fixed to the base 15. For example, the first nozzle 12 a is embedded in the base 15, and the outlet of the first nozzle 12 a is exposed to face the back side of the wafer W. The temperature-regulating module 11 a in FIG. 1 is illustrated as a heater configured to heat the liquid LQ for example, but the disclosure is not limited in this regard. In some embodiments, the temperature-regulating module 11 a is a cooler configured to cool the liquid LQ.

The second flow channel 10 b is configured to carry an etchant EC for etching the etch layer EL formed on the front side of the wafer W. The heater 11 b is coupled to the second flow channel 10 b. The heater 11 b is configured to heat the etchant EC in the second flow channel 10 b. The second mass flow controller 13 b is coupled to the second flow channel 10 b. The second mass flow controller 13 b is configured to measure and control the flow of the etchant EC at a particular range of flow rates. The second nozzle 12 b is coupled to the second flow channel 10 b and located right over a center of the front side of the wafer W. The second nozzle 12 b is configured to dispense the heated etchant EC onto the front side of the wafer W.

FIG. 2 is a flow chart of a method for etching an etch layer according to some embodiments of the present disclosure. As shown in FIG. 2 , with reference to FIG. 1 , the method for etching an etch layer at least includes steps S101-S103 shown below, and the steps can be performed by using the wafer etching apparatus 1 shown in FIG. 1 .

In step S101, an etchant EC is heated. As shown in FIG. 1 , the etchant EC can be heated by the heater 11 b in the second flow channel 10 b before dispensed onto the front side of the wafer W. In some embodiments, the wafer etching apparatus 1 can further includes a temperature controller (not shown) and a temperature sensor (not shown). The temperature sensor is coupled to the second flow channel 10 b and configured to sense the actual temperature of the heated etchant EC. The temperature controller is configured to adjust the actual temperature to a predetermined temperature by controlling the heater 11 b. Alternatively, in some embodiments, the temperature of the etchant EC is equal to the room temperature before etching the etch layer EL of the wafer W, that is, step S101 can be omitted.

Thereafter in step S102, a preheated/precooled liquid LQ is dispensed on a back side of a wafer W. In other words, in step S102, the liquid LQ is applied to the back side of the wafer W, and a temperature of the liquid LQ can be greater than, smaller than, or equal to a temperature of the wafer. As shown in FIG. 1 , the temperature of the liquid LQ can be controlled by the temperature-regulating module 11 a in the first flow channel 10 a before dispensed to the back side of the wafer W, and the first mass flow controller 13 a can control the flow rate of the liquid LQ dispensed out of the first nozzle 12 a. After dispensed out of the first nozzle 12 a, the liquid LQ flows along the gap formed between the base 15 and the back side of the wafer W, so as to control the temperature of the whole back side of the wafer W. Likewise, in some embodiments, the wafer etching apparatus 1 can further includes a temperature controller (not shown) and a temperature sensor (not shown). The temperature sensor is coupled to the first flow channel 10 a and configured to sense the actual temperature of the liquid LQ. The temperature controller is configured to adjust the actual temperature to a predetermined temperature by controlling the temperature-regulating module 11 a.

Thereafter in step S103, the etch layer EL is etched with the heated etchant EC. As shown in FIG. 1 , the second mass flow controller 13 b can control the flow rate of the heated etchant EC dispensed out of the second nozzle 12 b. In some embodiments, the chuck 14 is capable of rotating the wafer W in a plane, and the heated etchant EC is dispensed at the center of the front side of the wafer W. Therefore, the dispensed etchant EC can thus be uniformly distributed from the center to a peripheral edge of the front side of the wafer W to etch the etch layer EL.

As shown in FIG. 2 , steps S103 is performed during step S102, that is, etching the etch layer EL with the heated etchant EC is performed during dispensing the liquid LQ on the back side of the wafer W. In some embodiments, step S102 can be continuously performed to control the temperature of the back side of the wafer W and to make the dispensed liquid LQ form a steady flow at the gap between the base 15 and the back side of the wafer W, and step S103 is then performed to etch the etch layer EL on the front side of the wafer W.

In some embodiments, the etchant EC is phosphoric acid, and the liquid LQ is different from the etchant EC, but the disclosure is not limited in this regard. For example, the liquid LQ is water, but the disclosure is not limited in this regard.

With the foregoing configuration, it can be seen that the temperature of the wafer W is controlled during or before dispensing the heated etchant EC. As a result, the method for etching an etch layer and the wafer etching apparatus 1 of the disclosure can well regulate and control temperature (by reducing temperature variation between the dispensed etchant EC and the heated/cooled wafer W), rapidly ramp temperature, and get better uniformity across the wafer W. In some embodiment, to further reduce the temperature fluctuation across the wafer W, a difference between the temperature of the liquid LQ and a temperature of the heated etchant EC is smaller than a difference between the temperature of the liquid LQ and the temperature of the wafer W before the wafer W is heated/cooled and etched.

In addition, with the shrinking feature size the etch margins for substrates are getting ever smaller. This is especially relevant for the next generation 450 mm wafers where the large wafer size would bring in-wafer uniformity challenges. Presently, this is mitigated by using very low ER (etching rate)—through chemicals with ultralow dilution (1:1000, 1:1:50, etc). Challenges will exist for even these very low concentrations at larger wafer diameter. Traditionally, if the etching amount has to be adjusted, process time, chemical temperature, and chemical concentration have to be changed.

However, with the foregoing configuration of the present disclosure, trends of the etch profile of the etch layer EL on the front side of the wafer W can be effectively controlled, and the trends are observed and obtained experimentally and illustrated in FIG. 3A and FIG. 3B. FIG. 3A is a diagram of etch profile of the etch layer EL on the front side of the wafer W under a process configuration, in which the X-Axis is distance from wafer W center and Y-Axis is the etch Amount. FIG. 3B is another diagram of etch profile of the etch layer EL on the front side of the wafer W under another process configuration.

As shown in FIG. 3 , in the process configuration, the temperature TE1 of the dispensed etchant EC at the center of the front side of the wafer W is 30° C., and the temperature TL1 of the dispensed liquid LQ at the center of the back side of the wafer W is 50° C. that is larger than the temperature TE1. After heat exchange via the wafer W, the temperature TE2 of the etchant EC at the peripheral edge of the front side of the wafer W is increased to 38° C., and the temperature TL2 of the liquid LQ at the peripheral edge of the back side of the wafer W is decreased to 42° C. It is noted that in the process configuration, the trend of the etch profile gradually rises from the center to the peripheral edge of the wafer W. That is, the slope of the process configuration (i.e., TE1<TL1) is positive.

In contrast, as shown in FIG. 3B, in the process configuration, the temperature TE1 of the dispensed etchant EC at the center of the front side of the wafer W is 50° C., and the temperature TL1 of the dispensed liquid LQ at the center of the back side of the wafer W is 30° C. that is smaller than the temperature TE1. After heat exchange via the wafer W, the temperature TE2 of the etchant EC at the peripheral edge of the front side of the wafer W is decreased to 42° C., and the temperature TL2 of the liquid LQ at the peripheral edge of the back side of the wafer W is increased to 38° C. It is noted that in the process configuration, the trend of the etch profile gradually drops from the center to the peripheral edge of the wafer W. That is, the slope of the process configuration (i.e., TE1>TL1) is negative. It is noted that the temperature values illustrated above are just estimates, which are intended to show how the method of the present disclosure works.

In the above process configurations, the wafer W serves as the separator between two flows (i.e., the etchant EC and the liquid LQ) with different temperatures. This setup can be modeled as a co-current heat exchanger. LMTD (Logarithmic mean temperature difference) determines the effectiveness of heat transfer and final temperature at wafer edge. The LMTD is defined as:

${LMTD} = \frac{{\Delta\; T_{A}} - {\Delta\; T_{B}}}{\ln\left( \frac{\Delta\; T_{A}}{\Delta\; T_{B}} \right)}$

where ΔTA is the temperature difference between the two streams at end A (i.e., the temperature difference between TE1 and TL1), and ΔTB is the temperature difference between the two streams at end B (i.e., the temperature difference between TE2 and TL2). In this setup that the heat exchange area increases as the square of radius, suggesting that the temp difference must fall very rapidly.

Therefore, according to the above process configurations, it can be seen that the trend of the etch profile of the wafer W can be effectively controlled as needed by adjusting the temperature TE1 of the dispensed etchant EC and the temperature TL1 of the dispensed liquid LQ. As a result, the method for etching an etch layer and the wafer etching apparatus 1 of the disclosure can well regulate and control temperature (by reducing temperature variation between the dispensed etchant EC and the heated/cooled wafer W) and get better uniformity across the wafer W.

In some embodiments, the temperature of the back side of the wafer W can be controlled through a program (recipe) which varies temperature as a function of time or by the position of the first nozzle 12 a (or the position of the second nozzle 12 b), as illustrated in FIG. 4 . FIG. 4 is a partial view of a wafer etching apparatus 1 according to some embodiments of the present disclosure. As shown in FIG. 4 , the wafer etching apparatus 1 also includes the first flow channel 10 a, the second flow channel 10 b, the temperature-regulating module 11 a, the heater 11 b, the first nozzle 12 a, the second nozzle 12 b, the first mass flow controller 13 a, the second mass flow controller 13 b, the chuck 14, and the base 15. Compared with some embodiment such as FIG. 1 shows, the first nozzle 12 a shown in FIG. 4 is embedded in the base 15, and the outlet of the first nozzle 12 a is exposed to face the back side of the wafer W and aligned with a location between the center and the peripheral edge of the back side of the wafer W. As a result, the liquid LQ is dispensed at the location between the center and the peripheral edge of the back side of the wafer W.

In some embodiments, the backside nozzle may be fixed or maybe scan capable. For example, FIG. 5 is a partial view of a wafer etching apparatus 2 according to some embodiments of the present disclosure. As shown in FIG. 5 , the wafer etching apparatus 2 also includes the first flow channel 10 a, the second flow channel 10 b, the temperature-regulating module 11 a, the heater 11 b, the first nozzle 12 a, the second nozzle 12 b, the first mass flow controller 13 a, the second mass flow controller 13 b, and the chuck 14. Compared with some embodiments such as FIG. 1 and FIG. 2 show, the wafer etching apparatus 2 of shown in FIG. 5 further includes a nozzle actuator 26 and a modified base 25. The nozzle actuator 26 is connected to the first nozzle 12 a. The nozzle actuator 26 is configured to move the first nozzle 12 a along the back side of the wafer W along a pre-programmed path between a center and a peripheral edge of the back side of the wafer W. The base 25 has a passage 250 for allowing the movement of the first nozzle 12 a. The liquid LQ dispensed from the first nozzle 12 a flows along a gap formed between the base 25 and the back side of the wafer W.

In some embodiments, the wafer etching apparatus 1 may have a fixed first nozzle 12 a and scan the wafer W using a movable stage (not shown) holding the wafer W.

FIG. 6A is a partial view of a wafer etching apparatus 3 according to some embodiments of the present disclosure, in which the liquid LQ is dispensed to the wafer W. FIG. 6B is another partial view of FIG. 6A, in which the heated etchant EC is dispensed to the wafer W.

As shown in FIG. 6A and FIG. 6B, the wafer etching apparatus 3 also includes the first flow channel 10 a, the second flow channel 10 b, the temperature-regulating module 11 a, the heater 11 b, the first nozzle 12 a, the second nozzle 12 b, the first mass flow controller 13 a, the second mass flow controller 13 b, and the chuck 14 without the base 15. Compared with the embodiment such as in FIG. 1 shows, the first nozzle 12 a shown in FIG. 6A and FIG. 6B is configured to dispense the liquid LQ onto the front side of the wafer W.

FIG. 7 is a flow chart of a method for etching an etch layer according to some embodiments of the present disclosure. As shown in FIG. 7 , with reference to FIG. 6A and FIG. 6B, the method for etching an etch layer at least includes steps S201-S203 shown below, and the steps can be performed by using the wafer etching apparatus 3 shown in FIG. 6A and FIG. 6B.

In step S201, an etchant EC is heated. As shown in FIG. 6A and FIG. 6B, the etchant EC can be heated by the heater 11 b in the second flow channel 10 b before dispensed onto the front side of the wafer W. In some embodiments, the wafer etching apparatus 3 can further includes a temperature controller (not shown) and a temperature sensor (not shown). The temperature sensor is coupled to the second flow channel 10 b and configured to sense the actual temperature of the heated etchant EC. The temperature controller is configured to adjust the actual temperature to a predetermined temperature by controlling the heater 11 b. Alternatively, in some embodiments, the temperature of the etchant EC is equal to the room temperature before etching the etch layer EL of the wafer W, that is, step S201 can be omitted.

Thereafter in step S202, a preheated/precooled liquid LQ is dispensed on a back side of a wafer W. As shown in FIG. 6A, the temperature of the liquid LQ can be controlled by the temperature-regulating module 11 a in the first flow channel 10 a before dispensed to the front side of the wafer W, and the first mass flow controller 13 a can control the flow rate of the liquid LQ dispensed out of the first nozzle 12 a. Likewise, in some embodiments, the wafer etching apparatus 3 can further includes a temperature controller (not shown) and a temperature sensor (not shown). The temperature sensor is coupled to the first flow channel 10 a and configured to sense the actual temperature of the liquid LQ. The temperature controller is configured to adjust the actual temperature to a predetermined temperature by controlling the temperature-regulating module 11 a. In some embodiments, the chuck 14 is capable of rotating the wafer W in a plane, and the liquid LQ is dispensed at the center of the front side of the wafer W. Therefore, the dispensed liquid LQ can thus be uniformly distributed from the center to the peripheral edge of the front side of the wafer W to heat/cool the wafer W.

Thereafter in step S203, the etch layer EL is etched with the heated etchant EC. As shown in FIG. 6B, the second mass flow controller 13 b can control the flow rate of the heated etchant EC dispensed out of the second nozzle 12 b. In some embodiments, the chuck 14 is capable of rotating the wafer W in a plane, and the heated etchant EC is dispensed at the center of the front side of the wafer W. Therefore, the dispensed etchant EC can thus be uniformly distributed from the center to the peripheral edge of the front side of the wafer W to etch the etch layer EL.

Compared with the method shown in FIG. 2 , step S203 of the method shown in FIG. 7 is performed after step S202, that is, etching the etch layer EL with the heated etchant EC is performed after dispensing the liquid LQ on the front side of the wafer W. When the liquid LQ is dispensed on the front side of the wafer W to control the temperature of the front side of the wafer W, the second mass flow controller 13 b controls the heated etchant EC not to be dispensed out of the second nozzle 12 b. After the temperature of the front side of the wafer W is controlled by the liquid LQ to a certain predetermined condition, the first mass flow controller 13 a stops the liquid LQ from continuously dispensing, and then the second mass flow controller 13 b controls the heated etchant EC to be dispensed out of the second nozzle 12 b to etch the heated/cooled wafer W.

With the foregoing configuration, it can be seen that the temperature of the front side of the wafer W is controlled before dispensing the heated etchant EC. As a result, the method for etching an etch layer and the wafer etching apparatus 3 of the disclosure can well regulate and control temperature (by reducing temperature variation between the dispensed etchant EC and the heated/cooled wafer W), rapidly ramp temperature, and get better uniformity across the wafer W.

FIG. 8A is a partial view of a wafer etching apparatus 4 according to some embodiments of the present disclosure, in which the liquid LQ is dispensed to the wafer W. FIG. 8B is another partial view of FIG. 8A, in which the heated etchant EC is dispensed to the wafer W. As shown in FIG. 8A and FIG. 8B, the wafer etching apparatus 4 also includes the first flow channel 10 a, the second flow channel 10 b, the temperature-regulating module 11 a, the heater 11 b, the first mass flow controller 13 a, the second mass flow controller 13 b, and the chuck 14 without the base 15. Compared with some embodiment such as FIG. 6A and FIG. 6B show, the wafer etching apparatus 4 shown in FIG. 8A and FIG. 8B includes a single nozzle 42 coupled to the first flow channel 10 a and the second flow channel 10 b. The nozzle 42 is configured to dispense the liquid LQ and the heated etchant EC onto the front side of the wafer W sequentially. Therefore, the method shown in FIG. 7 can also performed by the wafer etching apparatus 4 shown in FIG. 8A and FIG. 8B.

FIG. 9 is a partial view of a wafer etching apparatus 5 according to some embodiments of the present disclosure.

As shown in FIG. 9 , the wafer etching apparatus 5 also includes the first flow channel 10 a, the second flow channel 10 b, the temperature-regulating module 11 a, the heater 11 b, the first nozzle 12 a, the second nozzle 12 b, the first mass flow controller 13 a, the second mass flow controller 13 b, and the chuck 14 without the base 15. Compared with some embodiment such as FIG. 1 shows, the wafer etching apparatus 5 shown in FIG. 9 further includes a third flow channel 50 c, a temperature-regulating module 51 c, a third nozzle 52 c, and a third mass flow controller 53 c. The first flow channel 10 a is configured to carry a first liquid LQ1 for controlling a temperature of a back side of the wafer W. The temperature-regulating module 11 a is coupled to the first flow channel 10 a. The temperature-regulating module 11 a is configured to heat/cool the first liquid LQ1 in the first flow channel 10 a. The first mass flow controller 13 a is coupled to the first flow channel 10 a. The first mass flow controller 13 a is configured to measure and control the flow of the first liquid LQ1 at a particular range of flow rates. The first nozzle 12 a is coupled to the first flow channel 10 a. The first nozzle 12 a is configured to dispense the first liquid LQ1 to a back side of the wafer W. The third flow channel 50 c configured to carry a second liquid LQ2 for controlling the temperature of the back side of the wafer W. The temperature-regulating module 51 c is coupled to the third flow channel 50 c. The temperature-regulating module 51 c is configured to control the temperature of the second liquid LQ2 in the third flow channel 50 c. The third nozzle 52 c is coupled to the third flow channel 50 c. The third mass flow controller 53 c is coupled to the third flow channel 50 c. The third mass flow controller 53 c is configured to measure and control the flow of the second liquid LQ2 at a particular range of flow rates. The third nozzle 52 c is configured to dispense the second liquid LQ2 to the back side of the wafer W. The temperature-regulating module 51 c in FIG. 9 is illustrated as a heater configured to heat the second liquid LQ2 for example, but the disclosure is not limited in this regard. In some embodiments, the temperature-regulating module 51 c is a cooler configured to cool the second liquid LQ2.

With the foregoing configuration, the wafer W can also be preheated/precooled during or before dispensing the heated etchant EC by using the wafer etching apparatus 5 shown in FIG. 9 and the method shown in FIG. 2 , so as to well regulate and control temperature (by reducing temperature variation between the dispensed etchant EC and the heated/cooled wafer W), to rapidly ramp temperature, and to get better uniformity across the wafer W.

FIG. 10 is a partial view of a wafer etching apparatus 6 according to some embodiments of the present disclosure.

As shown in FIG. 10 , the wafer etching apparatus 6 also includes the first flow channel 10 a, the second flow channel 10 b, the third flow channel 50 c, the temperature-regulating module 11 a, the heater 11 b, the temperature-regulating module 51 c, the first nozzle 12 a, the second nozzle 12 b, the first mass flow controller 13 a, the second mass flow controller 13 b, the third mass flow controller 53 c and the chuck 14 without the base 15. Compared with some embodiments such as FIG. 9 shows, the wafer etching apparatus 6 further includes a mixer 66 without the third nozzle 52 c. The mixer 66 is coupled with the first flow channel 10 a and the third flow channel 50 c such that the first liquid LQ1 and the second liquid LQ2 combine to form a mixture. The first nozzle 12 a is coupled to the mixer 66. The first nozzle 12 a is configured to dispense the mixture to a back side of the wafer W.

With the foregoing configuration, the wafer W can also be preheated/precooled during or before dispensing the heated etchant EC by using the wafer etching apparatus 6 shown in FIG. 10 and the method shown in FIG. 2 , so as to well regulate and control temperature (by reducing temperature variation between the dispensed etchant EC and the heated/cooled wafer W), to rapidly ramp temperature, and to get better uniformity across the wafer W.

FIG. 11 is a partial view of a wafer etching apparatus 7 according to some embodiments of the present disclosure.

As shown in FIG. 11 , the wafer etching apparatus 7 also includes the second flow channel 10 b, the heater 11 b, the second nozzle 12 b, the second mass flow controller 13 b, and the chuck 14 without the base 15. Compared with above embodiments, the wafer etching apparatus 7 further includes a temperature-regulating module 71 a thermally connected to the wafer W. In detail, the temperature-regulating module 71 a is thermally connected to the back side of the wafer W, but the disclosure is not limited in this regard. The temperature-regulating module 71 a is configured to control the temperature of the back side of the wafer W. In some embodiments, etching the etch layer EL with the heated etchant EC is performed during preheating/precooling the wafer W by using the temperature-regulating module 71 a. In some embodiments, etching the etch layer EL with the heated etchant EC is performed after preheating/precooling the wafer W by using the temperature-regulating module 71 a.

With the foregoing configuration, the wafer W can also be preheated/precooled during or before dispensing the heated etchant EC by using the wafer etching apparatus 7 shown in FIG. 11 , so as to well regulate and control temperature (by reducing temperature variation between the dispensed etchant EC and the heated/cooled wafer W), to rapidly ramp temperature, and to get better uniformity across the wafer W.

According to the foregoing recitations of the embodiments of the disclosure, it can be seen that the method for etching an etch layer and the wafer etching apparatus of the disclosure is proposed to preheat/precool the wafer before dispensing the heated etchant. Furthermore, the etch profile of the wafer can be effectively controlled as needed by adjusting the temperature of the dispensed etchant and the temperature of the dispensed liquid. As a result, the disclosure can well regulate and control temperature, rapidly ramp temperature, and get better uniformity across the wafer.

According to some embodiments, a method comprises rotating a wafer, dispensing a liquid from a center of the wafer to an edge of the wafer to control a temperature of the wafer, and etching an etch layer of the wafer with an etchant during or after dispensing the liquid.

According to some embodiments, a method comprises controlling a temperature of a liquid, dispensing the liquid to a wafer to control a temperature of the wafer, after controlling the temperature of the liquid and before dispensing the liquid to the wafer, measuring and controlling a flow rate of the liquid, and etching an etch layer of the wafer with an etchant during or after dispensing the liquid.

According to some embodiments, a method comprises heating an etchant, heating or cooling a wafer to reduce a difference between a temperature of the etchant and a temperature of the wafer, and etching an etch layer of the wafer with the etchant after heating the etchant and during or after heating or cooling the wafer.

Although the present disclosure has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein.

It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present disclosure without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the present disclosure cover modifications and variations of this disclosure provided they fall within the scope of the following claims.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure. 

What is claimed is:
 1. A method comprising: controlling a temperature of a liquid, wherein the liquid is water; dispensing the liquid by a first nozzle directed to a front side of a wafer to control a temperature of the wafer; after controlling the temperature of the liquid and before dispensing the liquid to the wafer, measuring and controlling a flow rate of the liquid; and etching an etch layer of the wafer with an etchant after dispensing the liquid, comprising: controlling a temperature of the etchant; and dispensing the etchant to the wafer to control the temperature of the wafer.
 2. The method of claim 1, further comprising: dispensing the liquid by the first nozzle directed to a center of the wafer.
 3. The method of claim 1, further comprising: dispensing the liquid by the first nozzle directed between a center and an edge of the wafer.
 4. The method of claim 1, wherein etching the etch layer of the wafer further includes: after controlling the temperature of the etchant and before dispensing the etchant to the wafer, measuring and controlling a flow rate of the etchant.
 5. The method of claim 1, further comprising: dispensing the etchant by a second nozzle directed to the front side of the wafer.
 6. The method of claim 5, wherein the first nozzle is closer to an edge of the wafer than the second nozzle.
 7. The method of claim 1, wherein the etch layer is a silicon nitride layer.
 8. The method of claim 1, wherein etching the etch layer of the wafer further comprises patterning the etch layer by using the etchant.
 9. The method of claim 1, wherein the etchant is dispensed from the first nozzle.
 10. A method comprising: heating a first liquid to a first temperature; cooling a second liquid to a second temperature different from the first temperature; measuring and controlling a first flow rate of the heated first liquid and a second flow rate of the cooled second liquid; combining the heated first liquid with the cooled second liquid to form a mixture with a third temperature different from the first and second temperatures; dispensing the mixture to a wafer after measuring and controlling the first and second flow rates; and etching an etch layer of the wafer with an etchant during or after dispensing the mixture.
 11. The method of claim 10, further comprising heating the etchant prior to etching the etch layer of the wafer.
 12. The method of claim 11, wherein heating the etchant is such that a fourth temperature of the etchant is higher than the third temperature of the mixture.
 13. The method of claim 10, wherein dispensing the mixture to the wafer comprises: dispensing the mixture by a nozzle embedded in a base below the wafer, wherein the mixture is dispensed into a gap formed between the wafer and the base.
 14. A method comprising: controlling a flow rate of a liquid; after controlling the flow rate of the liquid, dispensing the liquid to a wafer by a nozzle, wherein a temperature of the liquid is different from a temperature of the wafer prior to dispensing the liquid; etching an etch layer of the wafer with an etchant after controlling the flow rate of the liquid and after dispensing the liquid to the wafer, wherein the etchant is different from the liquid; adjusting the temperature of the liquid based on a temperature of the etchant; and moving the nozzle from a center of the wafer toward an edge of the wafer during dispensing the liquid.
 15. The method of claim 14, wherein dispensing the liquid to the wafer comprises dispensing the liquid to a backside of the wafer.
 16. The method of claim 14, wherein dispensing the liquid to the wafer comprises dispensing the liquid to the etch layer of the wafer.
 17. The method of claim 14, further comprising controlling the temperature of the etchant prior to etching the etch layer of the wafer with the etchant.
 18. The method of claim 17, wherein controlling the temperature of the etchant is such that a difference between the temperature of the liquid and the temperature of the etchant is smaller than a difference between the temperature of the liquid and the temperature of the wafer prior to dispensing the liquid.
 19. The method of claim 14, further comprising measuring and controlling a flow rate of the etchant.
 20. The method of claim 14, wherein the nozzle is embedded in a base below the wafer, and moving the nozzle from the center of the wafer toward the edge of the wafer is such that the liquid flows along a gap formed between the wafer and the base. 